How to open ContentPage with parameter in Shell

Question

gays! I use Xamarin.Forms, Shell and want to make TabBar to open pages

<TabBar>
    <ShellContent Title="Dictionary" ContentTemplate="{DataTemplate pages:WordPage}" />
    <ShellContent Title="Tools" ContentTemplate="{DataTemplate pages:ToolsPage}" />
</TabBar>

But a problem: class WordPage has next signature public WordPage(bool _transl) and I unable to open this page by xaml due parameter. I didn't find any examples how to create TabBar in C#. May be anybody knows how to build TabBar in C# or any another idea how to open pages with parameter. Thanks a lot!